1. Field of the Invention
The present invention pertains to an endless power transmission chain drive arrangement including a roller type chain having elastomeric bushings or rollers engageable with the chain sprocket for distributing the driving forces between sprocket teeth, reducing running friction and noise level and being adapted to run in a fluid of relatively low lubricity. The chain drive arrangement is particularly advantageous for use in conjunction with relatively low head fluid dynamic motors.
2. Background Art
Although roller chain drives are well known as power transmitting devices, there are certain disadvantages of conventional roller chains which have been overcome prior to the development of the present invention. For example, conventional roller chains utilize a relatively rigid bushing supporting a rigid roller which is engageable with the sprocket teeth. Practical limitations in the manufacture of conventional roller chains and sprockets require that the sprocket teeth be designed with the assumption that the maximum tensile load on the chain is imposed on one tooth. Even though as a practical matter, tooth and roller deflection permits some distribution of the load amongst the sprocket teeth actually engaged with the chain, this is largely indeterminate in conventional roller chain arrangements and, accordingly, the sprocket must be designed with the assumption that one tooth will experience the maximum chain load.
Moreover, although roller chains are basically low friction mechanical power transmission devices, virtually all applications of roller chains could benefit by improvements in mechanical efficiency as well as noise reduction. There are also several applications of roller chain drives wherein lubrication is a problem and the chain is either arranged such that no lubricant can be applied or the lubricating medium is of relatively low lubricity.
One particularly advantageous application of roller chain drives is in connection with a fluid dynamic or foil type motor for producing power with relatively low fluid heads such as may be found in applications of power production utilizing the hydraulic head in canals or natural streams and rivers. The basic concept of the low head foil type motor is also useful in converting wind energy. Some examples of improved power producing fluid foil type motors are disclosed in my U.S. Pat. No. 4,049,300. Although the improved chain drive of the present invention is particularly advantgeously used with a fluid dynamic foil type motor, the salient features of the invention may be utilized in other types of chain drives.